1. Field of the Invention
In an aspect, the invention relates to treatment of cancer, more particularly to coadministration of lucanthone and radiation for treatment of cancer.
2. Description of the Related Art
Management of patients with central nervous system (CNS) cancers remains a formidable task. Conventional chemotherapy administered systemically as a monotherapy tends not to be very effective because conventional chemotherapeutic agents tend not to reach portions of the CNS in effective amounts, primarily because of the blood-brain barrier. For example, etoposide and actinomycin D, two commonly used oncology agents that inhibit topoisomerase II, fail to cross the blood-brain barrier in useful amounts. Radiation therapy improves median survival. P. L. Kornblith et al, Chemotherapy for Malignant Gliomas, J. Neurosurg. 68: 1-17 (1988). This document, and all others cited to in this patent, is incorporated by reference as if reproduced fully herein. The benefit of radiotherapy, however, is limited by several factors. Although intrinsic radioresistance and rapid cellular proliferation may contribute to therapeutic inefficacy, dose escalation has not yet yielded superior results and is limited by the radiation tolerance of normal brain as reported by O. M. Solazar et al., High Dose Radiation Therapy in the Treatment of Malignant Gliomas: Final Report, Int. J. Radial. Oncol. Biol. Phys., 3: 1733-1740 (1979).
Combinations of chemotherapy and radiation have been experimented with in the treatment of CNS cancers. The additional use of nitrosoureas adds a modest gain for selected patients. M. D. Walker, Randomized Comparisons of Radiotherapy and Nitrosoureas for the Treatment of Malignant Glioma After Surgery, N. Eng. J. Med., 303: 1323-1329 (1980). U.S. Pat. No. 5,637,085 to Cardinale, with an issue date of Jun. 10, 1997, discloses a method and composition for intralesional therapy of solid cancer tumors, and especially brain tumors, comprising delivering a compound of a 1,2,4-benzotriazine oxide contained in a biodegradable, slow release polymer and subjecting the cancer tumors to irradiation therapy.
A problem with combining chemotherapy and radiation is that the blood-brain barrier interferes with transport of the chemotherapeutic agent into areas of the CNS, just as in monotherapy using chemotherapeutic agents. This reduces effectiveness of such therapies. For instance, compounds such as etoposide may be included in many multidrug protocols in medical oncology. However, etoposide crosses the blood-brain barrier poorly, thereby restricting its use in patients with central nervous system (CNS) lesions. The rapid induction of secondary leukemia in 1%-5% of patients is an obvious disadvantage of etoposide. Despite development of a number of different protocols, the overall survival of patients with CNS lesions such as glioblastoma multiforme, treated with surgery, radiation and chemotherapy, remains a dismal ten per cent.
There is therefore a need for a combination of chemotherapeutic agents and radiation that addresses the problems noted above.
In an aspect, the invention relates to a method of treating a cancer of the central nervous system in a host comprising administering radiation to the host, and administering lucanthone to the host; wherein the radiation and lucanthone are administered in amounts effective to cause the arrest or regression of the cancer of the central nervous system in the host. In another aspect, the invention relates to a method of treating tumors of the central nervous system comprising inducing base damage to a tumor cell""s DNA, and inhibiting excision repair of that damage by providing lucanthone to the cell.
The inventor has unexpectedly discovered that lucanthone may be advantageously administered, together with administration of radiation, in the treatment of cancers of the central nervous system, wherein the radiation and lucanthone are administered in amounts effective to cause the arrest or regression of the cancer of the central nervous system in the host.
Part of lucanthone""s particular advantage in treating central nervous system cancers is that the inventor has established lucanthone""s surprising ability to cross the blood-brain barrier in test animals, such as mice and rats. The inventor also has inferred its surprising ability to cross the barrier in humans. Therefore, lucanthone may be administered in physiologically tolerable amounts so as to have activity in the central nervous system, whereas other chemotherapeutic or radiosensitizing agents may not be so administered.
Lucanthone is a chemotherapeutic or radiosensitizing intercalating agent. For convenience, the term lucanthone is taken to include lucanthone proper, as 1-diethylaminoethylamino-4-methyl-10-thiaxanthenone, together with physiologically tolerated derivatives, analogs, and salts thereof. Such physiologically tolerated derivatives, analogs, and salts include, but are not limited to, Hycanthone, indazole analogues of lucanthone, and other analogs such as those disclosed in Thomas Corbett et al., Antitumor Activity of N-[[1-[[2-(diethylamino)ethyl]amino]-9-oxo-9H-thiaxanthen-4-yl]methyl]methanesulfonamide (WIN33377) and analogues, Exp. Opin. Invest. Drugs 3:1281-1292 (1994); and Mark P. Wentland et al., Anti-solid Tumor Efficacy and Preparation of N-[[1-[[2-(diethylamino)ethyl]amino]-9-oxo-9H-thiaxanthen-4-yl]methyl]methanesulfonamide (WIN33377) and Related Derivatives, Bioorg. and Med. Chem Lett. 4:609-614 (1994).
Lucanthone, which has been marketed as Nilodin or Miracil D, has been used as a treatment for schistomiasis. Lucanthone has been known to have an cytotoxic or cytostatic effect on growing cells. The enhanced joint lethal action of lucanthone and ionizing radiation in cells may be accounted for by the production of DNA double strand breaks (DSB) in cleavable complexes because of lucanthone""s inhibition of topoisomerase II, combined with the DSB induced by radiation alone. R. Bases, DNA Intercalating Agents as Adjuvants in Radiation Therapy, Int J Radiat Oncol Biol Phys 4:345-346 (1978) (editorial); R. E. Bases et al., Topoisomerase Inhibition by Lucanthone, an Adjuvant in Radiation Therapy, Int J Radiat Oncol Biol Phys 37:1133-1137 (1997).
Topoisomerase II may also be implicated in the mechanism of radiation induced DSB by an additional mechanism. When DNA bases are damaged by ionizing radiation, they are first removed by cells"" base excision repair enzymes, which first remove the damaged bases (by a glycosylase) and leave abasic sites. Removal of abasic sites is achieved in the second step, performed by endonucleases that cause strand scission and leave 3xe2x80x2 OH groups, which are required acceptors in DNA repair synthesis. Subsequent steps include removal of 5xe2x80x2 phosphate groups at the sites of excised bases, followed by gap filling by DNA polymerase xcex2, which inserts appropriate replacement nucleotides. DNA ligase completes repair by sealing in the replacement nucleotides.
If the abasic sites are not removed they could continue to act as endogenous topoisomerase II poisons, thereby promoting (lethal) DSB. P. S. Kingma et al., Abasic Sites Stimulate Double-stranded DNA Cleavage Mediated by Topoisomerase II: DNA Lesions as Endogenous Topoisomerase II Poisons. J Biol Chem 270:21441-21444 (1995).
It seems likely that topoisomerase II inhibitors, like lucanthone and Actinomycin D, which induce DNA double strand breaks by inhibiting topoisomerase II, might also enhance DNA double strand breaks in cell DNA by interfering with the removal of abasic sites in the second step of base excision repair described above. If so, the endogenous abasic site topoisomerase II poisons would persist in the DNA, leaving them in place to cause more double strand breaks over a longer time, thereby leading to a more than additive lethal effect. Unpublished data of the inventor suggests that lucanthone inhibits purified uracil DNA glycosylase and human apurinic apyrimidinic endonucleases at serum concentrations that would be readily achievable by oral dosing. Thus, lucanthone may be able to inhibit the crucial first two steps of post-radiation repair.
Previous results showed that lucanthone inhibited postradiation repair by enhancing potentially lethal and sublethal damage in Hela cells and in Chinese hamster cells. R. Bases, Enhancement of X-ray Damage in HeLa Cells by Exposure to Lucanthone (Miracil D) Following Radiation, Cancer Res 30:2007-2011 (1970); D. B. Leeper et al., The Effect of Lucanthone (Miracil D) on Sublethal Radiation Damage in Chinese Hamster Cells, Int J Radiat Oncol Biol Phys 4:219-227 (1978). In fact, in irradiated HeLa cells, lucanthone immediately induced a more than additive cell lethal effect, but when lucanthone was added to cultures several hours after radiation it could no longer enhance lethality beyond the simple addition of joint effects. Presumably, after several hours of culture, potentially lethal damage had already been repaired.
Furthermore, in patients with oropharyngeal cancer and metastatic lung lesions, radiation-induced tumor regression was significantly accelerated when patients received 10 mg/Kg lucanthone concurrent with radiation therapy. S. Turner et al., The Adjuvant Effect of Lucanthone (Miracil D) in Clinical Radiation Therapy, Radiology 114:729-731 (1975). Similar results were obtained with the joint treatment of patients with cervical cancer. M. P. Nobler et al., Lucanthone as a Radiosensitizing Agent in the Treatment of Carcinoma of the Cervix, Int J Radiat Oncol Biol Phys 4:1039-1044 (1978).
An advantage of lucanthone is that DNA replication requires topoisomerase II activity, thereby creating selective toxicity for cycling cells, such as cancerous cells. Normal brain cells, most of which do not cycle, would be therefore less sensitive to lucanthone-based therapy, and would be less likely to be non-selectively damaged. Furthermore, lucanthone""s effects on bone marrow and the gut are moderate and reasonably quickly reversible. Therefore, further chemotherapy and radiation after lucanthone therapy are not preempted due to chemotoxicity.
Lucanthone may be administered in a variety of routes, including orally, parenterally, intraperitoneally, intravenously, intraarterially, transdermally, sublingually, intramuscularly, rectally, transbuccally, intranasally, liposomally, via inhalation, vaginally, intraoccularly, via local delivery by catheter or stent, subcutaneously, intraadiposally, intraarticularly, intrathecally, or in a slow release dosage form. In a preferable embodiment, lucanthone is administered orally.
Lucanthone may be administered in an amount effective to cause arrest or regression of the cancer of the central nervous system in a host, when radiation is also administered to the host. More preferably, lucanthone may be administered in an amount effective to achieve a serum level of at least about 2.0 micrograms/milliliter, still more preferably at least about 3.0 micrograms/milliliter. When administering lucanthone orally, a preferable dosage is at least about 5 mg/Kg/day, more preferably at least about 10 mg/Kg/day. Oral doses of lucanthone may be administered once or more than once per day. If oral doses are administered more than once per day, a preferable number of doses is three doses per day. If administering lucanthone intravenously, a preferable dosage is 10 mg/kg continuously. Another preferable intravenous dosage is 3.3 mg/kg three times per day for a non-continuous (i.e. limited) period, such as two hours. Lucanthone may be administered intravenously using a conventional non-saline infusion fluid, such as 5% dextrose in water. Lucanthone dosing schedules may be for a variety of time periods, for example up to six weeks, or as determined by one of ordinary skill.
Lucanthone may be (co)administered in the practice of this invention together with other chemotherapeutic agents or other pharmaceuticals. (Co)administration in the context of this invention is defined to mean the administration of more than one therapeutic benefit in the case of a coordinated treatment to achieve an improved clinical outcome. Continuing, certain agents are believed to increase permeability through the blood-brain barrier. K. Matsukado et al., Intracarotid Low Dose Infusion Selectively Increases Tumor Permeability Through Activation of Bradykinin B2 Receptors on Malignant Gliomas, Brain Research 792:10-15 (1998). Such agents may be (co)administered with pharmaceuticals and lucanthone to increase the concentration of the pharmaceuticals in CNS tumor lesions. This may enhance the effect seen with administration of lucanthone and radiation.
Radiation may be administered in a variety of fashions. For example, radiation may be electromagnetic or particulate in nature. Electromagnetic radiation useful in the practice of this invention includes, but is not limited, to x-rays and gamma rays. In a preferable embodiment, supervoltage x-rays (x-rays greater than =4 MeV) may be used in the practice of this invention. Particulate radiation useful in the practice of this invention includes, but is not limited to, electron beams, protons beams, neutron beams, alpha particles, and negative pi mesons. The radiation may be delivered using conventional radiological treatment apparatus and methods, and by intraoperative and stereotactic methods. Additional discussion regarding radiation treatments suitable for use in the practice of this invention may be found throughout Steven A. Leibel et al., Textbook of Radiation Oncology (1998) (publ. W. B. Saunders Company), and particularly in Chapters 13 and 14. Radiation may also be delivered by other methods such as targeted delivery, for example by radioactive xe2x80x9cseeds,xe2x80x9d or by systemic delivery of targeted radioactive conjugates. J. Padawer et al., Combined Treatment with Radioestradiol lucanthone in Mouse C3HBA Mammary Adenocarcinoma and with Estradiol lucanthone in an Estrogen Bioassay, Int. J. Radiat. Oncol. Biol. Phys. 7:347-357 (1981). Other radiation delivery methods may be used in the practice of this invention.
The amount of radiation delivered to the desired treatment volume may be variable. In a preferable embodiment, radiation may be administered in amount effective to cause the arrest or regression of the cancer of a central nervous system in a host, when the radiation is administered with lucanthone. In a more preferable embodiment, radiation is administered in at least about 1 Gray (Gy) fractions at least once every other day to a treatment volume, still more preferably radiation is administered in at least about 2 Gray (Gy) fractions at least once per day to a treatment volume, even more preferably radiation is administered in at least about 2 Gray (Gy) fractions at least once per day to a treatment volume for five consecutive days per week. In a more preferable embodiment, radiation is administered in 3 Gy fractions every other day, three times per week to a treatment volume. In another more preferable embodiment, the first 23 fractions are administered to an initial treatment volume, while another 7 treatment fractions are delivered to a boost treatment volume. In yet another more preferable embodiment, a total of at least about 20 Gy, still more preferably at least about 30 Gy, most preferably at least about 60 Gy of radiation is administered to a host in need thereof. In another more preferable embodiment, radiation is administered to the whole brain, rather than to a treatment volume. When irradiating the whole brain, a maximum dosage of 30 Gy is recommended. In a most preferable embodiment, radiation is administered to the whole brain of a host, wherein the host is being treated for metastatic cancer.
In a preferable embodiment, the treatment volume comprises a contrast-enhancing lesion on a CT or MRI scan, more preferably a contrast-enhancing lesion and surrounding edema, still more preferably a contrast-enhancing lesion and surrounding edema on a CT or MRI scan plus at least about a 1 cm margin. In another preferable embodiment, the treatment volume comprises a contrast-enhancing lesion on a CT or MRI scan, still more preferably a contrast-enhancing lesion plus at least about a 1 cm margin, even more preferably a contrast-enhancing lesion plus at least about a 2.5 cm margin.
Treatment plans may include, but are not limited to, opposed lateral fields, a wedge pair of fields, rotation or multiple field techniques. CT-guided treatment planning is suggested to improve accuracy in the selection of field arrangements. Isodose distributions for the initial treatment volume and the cone-down treatment volume are suggested for all patients, including those with parallel opposed fields. Composite plans showing dose distribution to the initial treatment volume and the boost treatment volume are desirable. The minimum and maximum dose to the treatment volume are preferably kept to within about 10% of the dose at the center of the treatment volume.
A broad range of CNS cancers may be treated using the present invention. These cancers comprise both primary and metastatic cancers. In a preferable embodiment, lucanthone and radiation may be administered to patients suffering from primary brain tumors. Primary brain tumors treatable using the present invention include, but are not limited to glioblastoma multiforme, astrocytomas, medulloblastomas, acoustic neuromas, and tumors of the anterior and posterior pituitary. Cancers that have metastasized to the brain may also be treated using this invention. Such cancers include, but are not limited to, adenocarcinomas of the lung, squamous cell carcinomas of the lung, mammary adenocarcinomas, lymphomas, and leukemias.
It will be apparent to those skilled in the art that various modifications and variations can be made in the methods of the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents. Additionally, the following examples are appended for the purpose of illustrating the claimed invention, and should not be construed so as to limit the scope of the claimed invention.